Find IP Addresses on a Network

How to find an IP address

There are two ways to find IP addresses on network systems. You can find them manually or you can use an IP scanner, which is designed to automatically find the IP addresses within a certain range. 

With a scanner such as SolarWinds IPAM, you can run automated scans to identify new devices and more easily manage IP addresses.

The basic steps for manually creating a list of device IP addresses on a network include:

1. Get to the command line by opening a terminal window.
2. Type the right command for your system. On Linux, type the command “ifconfig” and press Return. On Windows, type the command “ipconfig” and press Return. 
3. Get more information by typing the command “arp -a.”
4. You should now see a basic list of the IP addresses for devices connected to your network.
5. You can then input this information into an information storage tool, like a spreadsheet, that you’ll need to update by hand each time you attempt a new discovery.

This process is unnecessarily time consuming and vulnerable to errors. Not only are you forced to manually run commands to find IP addresses whenever you want to see the devices connected to your network, but you also need to identify which of the IP addresses you find are new or have changed. 

An automated IP address discovery tool is designed to make it easier to find and manage IP addresses on a network.

How are IP addresses assigned?

There are two systems you can use to allocate IP addresses: static and dynamic.

With a static IP address system, you assign a specific IP address to each device on your network. Since these addresses don’t expire and are completely specific to each device, you need to keep a record of all the addresses you assign to prevent IP conflicts. 

A dynamic IP address system is a widely used system and doesn’t require users to manually assign specific IP addresses. The dynamic system revolves around the use of the Dynamic Host Configuration Protocol (DHCP). In this system, whenever a new device connects to the network, it must contact a central server operating the DHCP system to request an IP address. 

Unlike in the static system, the dynamic addresses allocated through DHCP aren’t permanent. Instead, each device receives an IP address on a “lease.” When the lease expires, the device will either retain the same address with a new lease or get a lease on a new address, abandoning the old IP address. Those abandoned IP addresses then become available. 

How to find unused IP addresses on my network

While IP addresses assigned through both static and dynamic systems can be abandoned, DHCP server addresses are more often at the center of IP address recovery. This is because the leases on addresses are limited and new leases may result in old IP addresses being abandoned without notice. 

Though the same steps apply for finding IP addresses in both static and dynamic systems, people often ask how to check for free IP addresses in a DHCP server rather than asking about static servers. 

Easily finding available IP addresses can be streamlined using an IP discovery tool. The amount of manual work required to keep track of all the leases on IP addresses in your network is already excessive. When you add the need to monitor when addresses become available versus when they’re leased to the same device again, it can be more difficult to manually recover IP addresses. 

With a discovery tool, the process of finding available IP addresses on your network is designed to be more straightforward. 

Why is finding free IP addresses important?

Finding free IP addresses and knowing what IP addresses are on your network are critical elements of effective IP address management for a network.

With IP addresses, you can quickly identify a device causing a problem and you can begin troubleshooting without wasting time trying to determine which device to target.

This is particularly important for networks where anyone can connect. Given the growth of BYOD policies and the resulting growth of BYOD Wi-Fi routers for employees, these open systems are becoming increasingly common. In these cases, it’s even more advisable to check and monitor IP addresses of the devices connected to your network.

How does IPAM help with finding and recovering IP addresses?

SolarWinds IP Address Manager is designed to automate the process of finding IP addresses, making it easier to find and recover abandoned addresses. IPAM’s active scanning lets you view transient IP addresses, so you can more easily identify and recover abandoned addresses as well as get real-time IP address information in just a few clicks.

With IPAM, you can also be sure you have a record of all the IP addresses on your network and can easily manage your scopes, DNS zones, and resource records.

With IPAM, you can automatically scan subnets and IP addresses for any changes as often as once every ten minutes and as little as once a week. You can also select which type of scan you want to perform. IPAM lets you choose between neighbor scans (using ARP tables), SNMP scans, and ICMP scans (ping sweeps). SolarWinds IPAM help you stay on top of IP address conflicts, subnets/scope depletion, and mismatched DNS entries, with the ability to automate static IP requests to help speed the deployment of devices.